Printing telegraph apparatus



Oct. 13, 1953 R. D. SALMON 2,655,555

PRINTING TELEGRAPH APPARATUS Filed May 11, 1951 4 Sheets-Sheet l Inventor \w vw $61,400 mow %/f/ Altorjey Oct. 13, 1953 D, SALMON 2,655,555

PRINTING TELEGRAPH APPARATUS Filed May 11 1951 4 Sheets-Sheet 2 as 3a 20 22 4/ 2a 28 F/GZ Inventor REGINALD D- 0 Attorney Oct. 13, 1953 Y R. D. SALMON 2,655,555

PRINTING TELEGRAPH APPARATUS Filed May 11, 19 51 4 Sheets-Sheet 3 A ttorn e y Filed May 11 1951 Oct. 13, 1953 v R. D. SALMON 2,655,555

PRINTING TELEGRAPH APPARATUS 4 Sheet's-Shet 4 2/ {mil III...

Inventor 75011440 0. snL/vwv A Horn e y Patented Get. 13, 1953 PRINTING TELEGRAPH APPARATUS Reginald Dennis Salmo Croydon, England, as-

signor to Creed and Company Limited, Croydon, England, a British company Application May 11, 1951, Serial No. 225,700 In Great Britain May 22, 1950 Claims.

This invention relates to printing telegraph apparatus and, more specifically, to mechanism for driving a rotatable member (such as a spline shaft connected to a type wheel) from a continuously rotating shaft and for stopping it in any desired on of a plurality of possible positions.

In my copending U. S. patent application bearing Serial No. 56,163, filed October 23, 1948 (now U. S. Patent No. 2,583,017), there is disclosed printing telegraph apparatus in which two stop arms are provided, separately and resiliently connected to the rotatable member and in which means is provided for causing these stop arms to be positioned on opposite sides of a stop member placed in their path. The rotatable member then oscillates about the position defined by the stop member and each stop arm can swing away from and back to the position of the stop member, the energy of the oscillating parts being damped so that the rotatable member is brought to rest in the position defined by the stop member.

According to the present invention there is provided printing telegraph apparatus comprising a rotatable member, a continuously rotating shaft, a friction clutch for driving said rotatable member from said shaft, a stop member for defining a stopping position for said rotatable member, a first stop arm resiliently connected to said rotatable member, a second stop arm resiliently connected to said rotatable member, a clutch lever rotatable independently of said stop arms, a clutch spring tending both to engage said friction clutch and to maintain said clutch lever in advance of said stop arms, means for bringing said stop member into the path of said stop arms and said clutch lever, means for causing said clutch lever when arrested by said stop member to oppose said clutch spring to disengage said friction clutch, means for causing said stop arms to be positioned on opposite sides of said stop member and damping means for bringing said rotatable member to rest in the position defined by said stop member after a limited amount of oscillation about said position.

One embodiment of the invention will now be described with reference to the accompanying drawings in which:

Fig. 1 is a side elevation partly in section of the mechanism for driving a spline shaft from a continuously rotating shaft and for stopping in any desired one of a plurality of possible positions,

Fig. 2 is an end elevation of the mechanism shown in Fig. 1,

Fig. 3 is a side elevation of the arrangement shown in Fig. 1 but with various parts omitted,

Figs. 4 to 8 are sections on the lines AA to EE of Fig. 3, and

Fig. 9 shows an end elevation of an alternative form of one of the details of the mechanism shown in the previous figures.

Referring to Fig. 1, a pinion 2 is driven from a continuously rotating motor-driven shaft (not shown). Pinion 2 is integral with one end of a driving tube l4 running in ball bearings 45 carried by the stationary body 33 of the translator assembly. To the other end of tube It is secured a clutch housing 3'! on the exterior of which are fitted cooling fins 49 (Fig. 3). Fitted inside the clutch housing 3'! is a clutch bush 38. All the above mentioned components rotate continuously all the time that the printer is in operation.

The type wheel (not shown) is driven from a spline shaft l9 (Fig. 1). The connection between the spline shaft l 9 and the continuously rotating shaft is made by means of a friction clutch comprising a clutch band 42 (Figs. 1 and 8) which is helically wound inside the clutch bush 38. One end of the clutch band 42 rest-s against an extension 26 of a driving arm I? clamped by a screw l8 to the spline shaft 19. The other end of clutch band 42 is acted on by one end of a clutch spring 29 (Fig. 8). The other end of clutch spring 29 is anchored in a tubular member 34 to which is spline-fitted a stop arm 25 (Fig, 5). This stop arm 25 has a downwardly extending projection 47 arranged to contact one side of a channel plate 2| secured by an adjusting screw it to driving arm I! and extension 26 thereof (Figs. 1 and 6). The natural tendency of clutch spring 29 is to contract and, assuming the spline shaft and driving arm to be stationary, the only end of the clutch spring which can move is the and pushing against one end of the clutch band 42. It can be seen from Fig. 8 that as spring 29 contracts as a result of its natural resilience its free end.

will tend to rotate by a small amount in an anticlockwise direction. This movement will be passed right through the clutch band 42 to the other end of the band which rests against the extension 26 of driving arm I! which last we have assumed to be stationary. As a result, clutch band 42 will be expanded inside the clutch bush 3'! and it is arranged that this amount of expansion is sufiicient to ensure that the clutch band becomes effectively locked to the clutch bush and is thus driven therewith. The direction of rotation is anti-clockwise in Figs. 2, 4, 5, 6, 7 and 8 and it will be seen from the last figure that the driving arm spline shaft and type wheel will all be rotated by the end of the clutch band pressing against driving arm extension 26.

As is well known in the art, the stopping position for the type wheel is determined by selecting one of a plurality of stop members by means of a plurality of specially cut permutation discs set in accordance with the respective elements of a received signal combination. In Fig. 1, the.

permutation discs (five in number -for a five unit code) are shown at |mounted on thestationary body 33. These permutation discs are assumed to be set by means of any wellrknown selector mechanism (not shown)- Resting on the periphery of discs I are twenty-six sets of rollers 9 carried in roller bearing frames riveted to stop members 4|. As soon as discs I assume positions corresponding to the combination peculiar to a particular stop member, the latter is drawn by its spring |3 into the path of stop arm 25. Each stop member is guided for angular movement by an individual rod l pivoted in a first guide ring |2 (Fig. 1)..at its free end. The stop members 4| are free to rise and fall (as selected) in slots cut in a second guide ring 39 (Fig. 2) and are positioned longitudinally by a third guide ring 40 (Fig. l).

The arrangements so far described provide the means for engaging a clutch to drive a spline shaft from a continuously rotating shaft and the means for selecting a stop member to determine the stopping position for the spline shaft and the type wheel driven thereby.

The present invention provides the means for positively disengaging the clutch before the rotating parts are actually arrested.

It has already been explained that the clutch was engaged by allowing clutch spring 29 to contract itself and thus to expand the clutch band 42 inside the clutch bush 31. In order to disengage the clutch the clutch spring. is opposed and the clutch band released by the means now to be described.

In addition to acting on :one end of the clutch band 42, spring 29 acts on a projection-48 of a clutch lever body 21 which is a running fit over tubular member 34. A clutch lever- 28 is splinefitted at its base to clutch lever body 21 and the radial distance from its centre of rotation to its tip is the same as that of stop arm 25. Hence, a selected stop member will be placed in its path also.

It will be seen from Fig. 8 that clutchspring 29 is effectively between stop arm 25 and clutch lever 28 hence the spring in addition to expanding clutch band 42 tends to advance clutch lever 28 (in the direction of rotation) relatively to stop arm 25. This results in the clutch lever 28 being the first component of the rotating as sembly to strike the selected stop member. on impact of the clutch lever with the stop member, a clockwise movement is passed through the clutch lever 28, clutch lever body 21 and projection 48 thereof to oppose spring 29 and relax the clutch band 42. This de-energises the clutch and the remaining rotation of the spline shaft will be due to the inertia of the parts driven thereby.

In order to prevent the stop arm 25 from rebounding means is provided for latching it once it has been arrested. The means for latching stop arm 25 comprises a latch 22 (Figs. 2 and 4) pivoted at to a second stop arm 23. An extension 46 of stop arm 23 is normally kept in contact (by means to be described later) with the opposite side of channel plate 2| from that engaged by extension 41 of stop arm 25. A latch spring 43 (Figs. 1 and 3) acts on one end of latch 22 to keep it in a position where it can engage a selectedstop-member. The relative positions of the two stop arms andthe clutch lever 28 are such that the latter is the first component to ..strike the selected stop member followed by latch 22 on stop arm 23 and lastly stop arm 25.

'Both stop arm 25 and clutch lever 28 are arrested by impact with the stop member but latch 22 .isiso constructed as to be lifted over the stop member and reach the position shown in Fig. 4 but not to pass over the stop member in the reverse direction.

In order to absorb the kinetic energy stored in the; rotating system a spring 32 (Fig. 1) is effectively connected between the stop arms 23 and 25 and this spring also serves to keep bothswp arms resiliently connected to the driving arm l1 and spline shaft IS in the manner now to beexplained.

Just as stop arm 25 .is spline-fitted to a tubular member 34 so stop arm 23 is spline-fitted -toa second tubular member 36 (Figs. 1 and 4). This second tubular member is a running fit over the spline shaft l9 and a running fit inside tubular member 34. It will be seen from Fig. 1 that the inner tubular member 36 is considerably longer than tubular member 34 and spring 32 is helically wound about the exposedlength of member 36. Member 34 is provided at the-endremote from the stop member 25 (the right hand end in Fig. 1) with a dog tooth engaging the left hand end of spring 32. A spring cap 35 fits over the left hand end of spring 32 to keep it in contact with the end of member 34. The right hand end of spring 32 engages a second dog tooth inside a cap 3| which is fitted to a collar 30. This collar 3|) is-not directly fixed to the inner tubular member 36 but is provided on the side remote from the dog tooth engaging the spring with .a plurality of ratchet teeth engaging a like number .of ratchet teeth on av second collar 8 which latter is splined to member 36.

It will now be evident that spring 32 is effectively between. stop arms 23 and 25 and itstension can be adjusted (as described later) tokeep extensions 46 and 41 of stop arms 23 and-25' respectively, in contact with the channel plate2| boltedto driving arm I! and hence secured to spline shaft 9.

When the rotating system (i. e; the spline shaft, type wheel and stop arms) overshoots, stop arm 23 is carried on in the direction of rotation but stop arm 25 remains in its arrested position.

Since spring 32 is connected between the two sto arms it is wound up and thus stores .up the energy of the rotating system. After a limited amount of overshoot in the forward direction, spring 32 accelerates the rotating system in the opposite direction thus bringing latch 22 into contact with the stop member and rotating stop arm 25 backwards. Latch 22..will not pass the stop member in the reverse direction consequently stop arm 23 is arrested and spring 32 again wound up. overshooting in each 'directionis continued until all the kinetic energy in the system has been absorbed by friction and the system is at rest.

In order to increase the damping of the stop arm assembly, stop arm 23, stop arm 25, a friction plate 24 (Fig. 1), thrust washers 3 and 4 and an oilite bush 5 are arranged to form a friction pack compressed by damping screws 44 (Fig. 2) which pass through spring ears. on driving arm ll. Screws 44 are adjusted to give the required amount of damping. Friction plate 24 also serves to prevent clutch band 42 from coming out of clutch bush 35 (this can be seen most clearly from Fig. 1).

To obtain the correct torque from'spring 32 in operation it is necessary to tension it slightly in the assembly of the unit and this is achieved in the following manner.

Collar 30 is provided with a number of peripheral holes into which may be inserted a rod for tightening. Twisting the collar to tension the spring causes the ratchet teeth on collar 30 to advance by one or more teeth with respect to collar 8 and if the amount of spring tension so obtained is satisfactory nothing further need be done in this direction. It may happen that the advance required is not equal to a whole number of teeth and provision is made for a finer adjustment on the Vernier principle. The second collar 8 may be removed from the spline shaft by removal of a split spring washer 6 and a retaining washer l. The number of splines on tubular member 36 are arranged to be only one or two different from the number of ratchet teeth on each collar. Thus a fine adjustment can be ob tained by removal of collar 8 and replacing it in a slightly different angular position before retightening the collar 30,

Movement of clutch lever 28 and clutch lever body 21 in a clockwise direction (Fig. 8) tensions clutch spring 29 and moves clutch band 42 clockwise and away from driving arm tip 26 so allowing clutch band 42 to release and disengage the clutch as previously described. This disengaging must be positive but not excessive. An adjustment is therefore considered essential and is obtained by rotation of adjusting screw I5 which moves driving arm tip 26 radially.

Turning to Fig. 9 there is shown an alternative form of latch member to replace stop arm 23 and latch 22. A single resilient blade 49 shaped as shown is splined directly onto the tubular member 36 and its upper extremity 50 is twisted to allow it to pass the selected stop member in the forward direction only.

While the principles of the invention have been described above in connection with specific embodiments, and particular modifications thereof, it is to be clearly understood that this description is made only by way of example and not as a limitation on the scope of the invention.

What is claimed is:

1. Printing telegraph apparatus comprising a rotatable member, a continuously rotating shaft, a friction clutch for driving said rotatable member from said shaft, a stop member for defining a stopping position for said rotatable member, a first stop arm resiliently connected to said rotatable member, a second stop arm resiliently connected to said rotatable member, a clutch lever rotatable independently of said stop arms, a clutch spring tending both to engage said friction clutch and to maintain said clutch lever in advance of said stop arms, means for bringing said stop member into the path of said stop arms and said clutch lever, means for causing said clutch lever 6. when arrested by said stop member to oppose said clutch spring to disengage said friction clutch, means for causing said stop arms to be positioned on opposite sides of said stop member and damping means for bringing said rotatable member to rest in the position defined by said stop member after a limited amount of oscillation about said position. I

2. Printing telegraph apparatus as claimed in claim 1 in which said clutch spring presses a clutch band into engagement both with a member driven from said continuously rotating shaft and with an arm rigidly connected to said rotatable member so as to constitute said friction clutch.-

3. Printing telegraph apparatus as claimed in claim 2 in which said clutch band is in the form of a closely wound helix, in which the member driven from said continuously rotating shaft comprises a cylindrical bush surrounding said helically wound clutch band and in which said clutch spring acts when unopposed to increase the diameter of said clutch band to cause it to grip the interior surface of said bush.

4. Printing telegraph apparatus comprising a rotatable member, a continuously rotating shaft, a friction clutch for driving said rotatable member from said shaft, a stop member for defining a stopping position for said rotatable member, a first and a second stop arm, a spring connected between said stop arms and said rotatable member to afford a resilient connection between said respective stop arms and said rotatable member, a clutch lever rotatable independently of said stop arms, a clutch spring tending both to engage said friction clutch and to maintain said clutch lever in advance of said stop arms, means for bringing said stop member into the path of said stop arms and said clutch lever, means for causing said clutch lever when arrested by said stop member to oppose said clutch spring to disengage said friction clutch, means for causing said stop arms to be positioned on opposite sides of said stop member and damping means for bringing said rotatable member to rest in the position defined by said stop member after a limited amount of oscillation about said position.

5. Printing telegraph apparatus as claimed in claim 4 in which said stop arms are adapted to be pressed by said spring into contact with opposite sides of an arm rigidly connected to said rotatable member.

6. Printing telegraph apparatus as claimed in claim 4 in which one of said stop arms is fixed to a first tubular member rotatable about the axis of said rotatable'member, in which the other of said stop arms is fixed to a second tubular member rotatable about said first tubular member and in which said spring is a torsion spring helically wound about said tubular members and attached at its ends to the respective ones of said tubular members.

7. Printing telegraph apparatus as claimed in claim 6 in which one end of said spring abuts against a projection on the end of one of said tubular members and in which the other end of said spring abuts against a similar projection on a collar adjustably connected to the other of said tubular members so as to permit of alteration being made in the tension of said spring.

8. Printing telegraph apparatus as claimed in claim 7 in which said collar is provided with a number of teeth arranged to engage the same number of teeth on a second collar, in which said second collar is spline-fitted to said other 8 tubular member, and in which .thamunber Lot 10. Printing telegraph appazams as claimed tooth on cash oizsaid eoilars difierstimm the in claim 9 in which said latch means is connumber oi splines onsaid other tubular memhcr stituted by a suitably shaped-blade of resilient bya comparatively small-,nnmberosozastopermaterial and- ,in which said spring means is mit ct accurate adiustment ortheiension 5 constituted by theresilience of said blade. Sam spnng' REGINALD DENNIS SALMON.

9. Printing telegraphsapparatus as. claimed. in claim 4 further comprising latch means. mounted on one of said stop armsiand so shapedas to 'W M inlmflmeoi this Mt ride over said stop memberupon impact there- 10 with during movement inone, direction of ro- UNITED STATES PATENTS tation only and spring means to: resting said Number Name Date latch means to original position. after. said im- 1,905,090 Griflith Apr. 25, 1933 pact. 2,271,673 Zenner. Feb. 3, 1942 

